Treatment and recovery of material by flotation



United States Patent TREATMENT AND RECOVERY OF MATERIAL BY FLOTATION David Weston, 129 Adelaide St. W., Toronto 1,

Ontario, Canada No Drawing. Filed Jan. 12, 1959, Ser. No. 786,009

Claims priority, application Canada Sept. 5, 1958 3 Claims. (Cl. 2099) This invention relates to the conditioning of material for metallurgical treatment such, for instance, as flotation or leaching, or other treatments where the advantages of the invention may be of benefit.

For purposes of conditioning material for metallurgical treatment, it is frequently desired to associate particulate reagents with particles of material prior to introduction of said material to the actual metallurgical treatment which it is intended to carry out. In general, the practice has been in the past to carry out such conditioning when the material is suspended in a liquid pulp. In many cases, wet conditioning of this nature requires an excessive rate of reagent consumption, and in general such wet conditioning is ineflective to promote slimes. In addition, a substantial amount of power is consumed in the course of such wet conditioning treatments.

I have now found that liquid reagents or reagents which may be placed in liquid form can be eifectively associated with the material to be treated while the latter is in the dry state. According to the invention, the reagent material may be applied to the material to be treated in any one of a number of different ways. If the material is originally in particulate form, such for instance as certain beach sands or tailings piles, the material may be tumbled in any conventional form of tumbling drum with the reagent added thereto at the desired rate in liquid form either as a spray or as drops added to the material as the latter is fed to the drum. Where the material is not already in particulate form and the comminution unit is for instance a dry ball mill, tube mill or dry pebble mill, the liquid reagent may be added in metered quantities to the feed to the mill before the latter is fed thereto or the appropriate quantity of reagent may be sprayed into the mill. If the comminution unit employed is one in which the material is removed in an :airstream, the reagent may be added in the same manner as it is added in the case of a dry ball mill, tube mill or dry pebble mill, and in addition there is a further alternative that the reagent may be added as a spray of coarse or fine droplets to the airstream. In any of the foregoing events, the particulate material is collected dry with a reagent on it and may be then subjected to storage in the dry state for such period as may be appropriate having regard to the particular materials and/or processes involved. The association of the liquid with the particulate material apparently arises by virtue of the free energy which appears on surfaces of freshly comrninuted material or which is produced in the tumbling action of already particulate material. In any event, the liquid will tend to coat the particulate material, and such coating will be carried to completion in a period of time which varies markedly as the characteristics of the material vary. Thus, the material may be completely coated in an effective manner by the time the treated material is collected from the milling system or tumbling system employed, or, on the other hand, additional time of storage in the dry state may be required in order to enable completion of the coating.

A typical example of the operation of the invention is in the application of liquid xanthate reagent to sulphide ores where the ore in its cornminuted state contains substantial quantities of slime. In such instance, the xanthate is added to the ore in any of the manners aforesaid at the rate which is empirically determined as the most economical for the ore concerned, and after a suitable period of dry storage the treated material is subjected to flotation or flotation preceded by a short period of wet conditioning in essentially conventional manner. The surprising result achieved is that with a comparatively low reagent consumption the xanthate has become associated with the mineral in the ore and is associated as well with the slimes as with the particles of larger size which are normally considered more suitable for flotation. Thus, the problem of slimes which is an outstanding problem in flotation is eliminated.

Another example of the operation of the invention is in preparing material for a leaching operation. In this case, it may be desired to use concentrated sulphuric acid as the reagent to be applied for instance to the leaching of a uranium ore. The calculated quantity of concentrated sulphuric acid is added in any of the manners described above, and after a period of dry storage during which the sulphuric acid associates itself preferentially with the mineralized particles of ore While it is essentially in the non-reactivated concentrated form, the thus conditioned material is slurried with a calculated quantity of water bringing the concentration of the sulphuric acid to the optimum value for purposes of the particular leach. In this way, a particularly high eificiency is attained in the solubilization of the mineral while using extremely economical quantities of acid. The volume of water is kept to a minimum and filtration problems which are always of extreme importance in the leaching of uranium are reduced to a minimum.

A third example of the operation of the invention is in the treatment of oxidized sulphide ores where the reagent employed is a sulphidizing agent. In such an operation, a calculated quantity of sulphidizing agent such as sodium polysulphide solution in concentrated form is applied to the ore in the manner above described, and the treated material is dry stored. The sulphidizing agent is found to associate itself preferentially with the mineralized particles eflfectively causing sulphidization of at least the surfaces of the oxidized particles, rendering the total mineral content amenable to flotation by conventional methods.

While I have explained the manner of operation of the process of the invention in relation to three principal types of metallurgical operation, it is to be understood that the above examples are given by way of illustration only. The method of the invention is a general method for applying liquid reagents to solid material, and there are, in so far as present knowledge is concerned, no limitations on its applicability. In particular, it may be mentioned that the process of the invention is extremely effective in the application of flotation agents to oxide ores such as hematite, uranium oxide, nickel oxide, and the like, such flotation reagents generally being of an oily nature and encompassing such materials as tall oil, fuel oil, fatty acids, and many other substances known in the art, and too numerous to mention.

What I claim as my invention is:

1. A method of recovering material by flotation which comprises providing the material to be treated in the dry particulate form characterized by free energy on the surface thereof, associating an amount of a liquid flotation reagent with the dry particulate material suflicient to reagentize the material, maintaining the material associated with said liquid reagent as a mixture essentially in the dry state for a predetermined period of time and then sub jecting the thus treated material to separation by flotation.

2. The method of claim 1 wherein the free energy on the surface of the particulate material is eflected through tumbling and during which flotation reagent is associated with the material.

3. A method of recovering material by flotation which comprises, adding an amount of a liquid flotation reagent 10 faces thereof with which the reagent becomes associated 15 4. and then subjecting the oomminuted material to separation by flotation.

References Cited in the file of this patent UNITED STATES PATENTS 1,175,331 Atwater Mar. 14, 1916 1,889,027 Washburn Nov. 29, 1932 1,985,076 Breger Dec. 18, 1934 2,334,258 Gavin Nov. 16, 1943 2,437,164 Kramer Mar. 2, 1948 2,944,666 Bunge July 12, 1960 FOREIGN PATENTS 568,755 Germany June 23, 1933 

